Interimage characteristics of silver halide dye developer image transfer systems



Oct. 1, 1968 R. W. BECKER 3,404,002

INTERIMAGE CHARACTERISTICS OF SILVER HALIDE DYE DEVELOPER IMAGE TRANSFER SYSTEMS Filed June 27, 1963 6 Sheets-Sheet l SUP/ 0R T MORAA/VT LA YER P00 CONTA/N/A/G PROCESS/N6 MArER/AL 72H- PROTECTIVE LAYER "'"\YELL0W DYE DEVELOPER LAYER M aREE/vsE/vs/rll/E EMULSION LAYER MAGENTA DYE DEVELOPER LAYER K m/rERLAYER RED "SENSITIVE EMULSION LAYER CYA/V DYE DEVELOPER LAYER SUPPOR 7' R/CHARD W EEC/(ER INVENTOR.

- BY REM/JR E ML;

A TTORNEYS Oct. 1, 1968 w, KE 3,404,002

INTERIMAGE CHARACTERISTICS OF SILVER HALIDE DYE DEVELOPER IMAGE TRANSFER SYSTEMS I Filed June 27, 1965 3 Sheets-Sheet 2' Cm/V DYE m/ NEUTRAL SCALE cm/v DYE //v RED scALE- /.0

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RICHARD w. BECKER INVENTOR ATTORNEYS Oct. 1, 1968 R. w. BECKER 3,404,002

INTERIMAGE CHARACTERISTICS OF SILVER HALIDE DYE DEVELOPER IMAGE TRANSFER SYSTEMS Filed June 27, 1963 5 Sheets-Sheet 5 'MA0E/vm DYE //v GREEN SCALE /.4

MAGENTA DYE I IV NEUTRAL 5CALE\ /.0

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MAGENTA 0Y5 m/ NEUTRAL 80A LE /.4

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RICHARD W BECKER INVENTOR BY @WM QE RWQQ ORIVEYS United States Patent INTERIMAGE CHARACTERISTICS OF SILVER HALIDE DYE DEVELOPER IMAGE TRANS- FER SYSTEMS Richard W. Becker, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey .Filed June 27, 1963, Ser. No. 291,056 12 Claims. (Cl. 96-3) The present invention relates to the art of photography, and more particularly, to multicolor diffusion transfer systems utilizing dye developers.

Compounds which contain in the same molecule both the chromophoric system of a dye and a photographic silver halide developing moiety have been described in the photographic art as useful compounds in photographic elements for preparing color images by diffusion transfer processes. Such compounds are commonly called dye developers. Photographic elements containing such dye developers generally comprise a plurality of photosensitive silver halide emulsions wherein each of the emulsions is selectively sensitized to a different region of the spectrum. A dye developer is positioned contiguous to the silver halide in each of such emulsions. Such a photoelement is processed with an alkaline solution and the latent image is developed in the negative image areas with the dye developers, this development immobilizing the dye developers in such negative image areas, and the dye developers in the unexposed areas diffuse to the surface imagewise and are transferred to a receiving sheet to form a positive color image. Such color diffusion transfer processes are disclosed in US. Patent 2,983,606, as well as elsewhere in the literature.

In such subtractive color systems utilizing dye developers, the dye moiety of the dye developers are not always true colors. For example, magenta dyes often have small amounts of blue light absorption and red light absorption. Similarly, yellow dyes and cyan dyes absorb small amounts of light other than blue and red light, respectively. The effect of small amounts of unwanted absorptions due to such minor deficiencies in dye developers'tends to produce dark and desaturated colors or color hue errors in color transfer prints. It is highly desirable to be able to compensate for such dye deficiencies in subtractive color processes utilizing dye developers.

It is accordingly an object of this invention to provide a novel method for correcting for unwanted absorptions of dye developers utilized in photographic diffusion transfer systems.

It is another object of this invention to provide a novel psycho-physical method for color correcting the dye developer transfer images resulting from photographic color diffusion transfer processes.

j Itis another object of this invention to provide photographic dye developer diffusion transfer prints having brighter and more saturated colors.

These and other objects of the invention are accomplished by utilizing in the negative or light-sensitive ele- .ment used in dye'developer diffusion transfer processes a higher molar proportion of iodide as mixed silver halide in one of the light-sensitive silver halide emulsion layers than in at least one. of the other silver halide emulsion layers in the negative element. More specifically, photographic elements useful in my invention comprise a support with superposed red, green and blue light-sensitive .silver halide emulsion layers and dye developers conthe respective contiguous silver halide emulsions. The

silver halide in at least one of the silver halide emulsion 3,404,002 Patented Oct. 1, 1968 ice layers contains at least about one mole percent more iodide as mixed silver halide than the silver halide in at least one of the other silver halide emulsion layers.

I have found that the use of more iodide as mixed silver halide crystals in the emulsion of at least one of the emulsion layers of photographic elements used in dye developer diffusion transfer systems as described herein produces highly desirable interimage effects which mani fest themselves in such improved properties as brighter and more saturated colors in the transfer prints prepared from such photographic elements. As is known in the art, certain interimage effects can be utilized to improve color reproduction in subtractive color processes. Reference is made to Journal of the Optical Society of America, volume 42, No. 9, pages 663-669, September 1952, wherein Hanson and Horton described the use of interimage effects to correct for unwanted absorptions of photographic dyes. I have found that such desirable interimage effects can be produced in photographic dye developer diffusion transfer systems by the use of photographic elements of the type described herein.

Color diffusion transfer systems utilizing dye developers of the type used in the photographic elements of the invention are well known in the art. Dye developers are relatively nondiffusible in the hydrophilic layers of photographic elements at neutral pH, but are diffusible in such substrates in the presence of alkaline processing solutions. Such compounds function as a silver halide developing agent and as a dye in photographic diffusion transfer sys tems. I described in considerable detail several typical classes of dye developers that can be suitably utilized in the present invention in my copending application Ser. No. 71,314, filed Nov. 23, 1960. Suitable dye developers are also disclosed in the following patents: Australian 220,279; German 1,036,640; British 804,971 and 804,973- 5; and French 1,168,292. Dye developers are characterized as having both a chromophoric or dye moiety and at least one moiety having a silver halide developing function. Particularly useful dye developers are those wherein the chromophoric moiety is an azo or anthraquinone dye moiety and the silver halide developing moiety is a benzenoid moiety such as hydroquinonyl moiety.

In the photographic elements useful in the invention, I prefer to incorporate the dye developers in the vehicles or carriers comprising the layers of the photographic element dissolved in high boiling solvents and dispersed as finely-divided droplets (e.g., less than about 5 microns). Typical high boiling solvents utilized to prepare dispersions of dye developers in the photographic vehicle for the dye developer are high boiling, water-immiscible organic liquids having a boiling point above about C. The high boiling solvent can be used alone in dissolving the dye developer and in forming the dispersion, or it can be mixed with a low boiling solvent (e.g., boiling at least 25 C. below the boiling point of the higher boiling solvent) or a water-soluble organic solvent, as an auxiliary solvent to facilitate solution of the dye developer. A preferred range of proportions of high boiling solvent to auxiliary solvent are 1/0 to 1/l0-0n a weight basis. Such auxiliary solvents can be readily removed from the high boiling solvent for example by air drying, a chilled, noodled dispersion or by continuous water washing. I described in detail several of such high boiling solvents and auxiliary solvents utilized for incorporating dye developers in my aforementioned copending application Ser. No. 71,314. Thedye developers can also be incorporated into vehicles soluble in organic solvents which are also solvents for the dye developer.

Likewise, other incorporating techniques for the dye developer such as ball-milling can'be utilized.

The silver halide used in preparing the light-sensitive emulsion layers of at least one of the silver halide emulsion layers of the photographic elements of the invention comprise at least one mole percent more iodide as mixed silver halide crystals, and generally, predominantly (i.e., at least 50 mole percent) iodide-containing mixed silver halide crystals wherein the iodide comprises about 1 to 20 mole percent of the mixed silver halide crystals and at least about 1 mole percent more iodide than any mixed silver halide crystals in at least one of the other silver halide emulsion layers. Minor proportionate amounts on a mole percent basis of silver chloride, silver bromide, silver iodide or mixtures thereof can also be utilized in such higher iodide-containing mixed silver halide emulsions. The emulsion layers having the lesser amounts of iodide-containing mixed silver halides can also contain mixed halides as Well as silver chloride, silver bromide, silver iodide or mixtures thereof. I prefer to utilize photographic elements wherein the silver halide is predominantly silver bromoiodide in all of the light-sen v sitive silver halide emulsion layers, and wherein the bluesensitive silver halide emulsion contains silver bromoiodide having at least one mole percent more iodide than the silver bromoiodide in the greenand red-sensitive emulsion layers. Conventional developing-out negativetype silver halide emulsions are utilized in preparing the present emulsions. As used herein the term mixed silverhalide refers to silver bromoiodide, silver chloroiodide, silver bromochloroiodide ormixtures thereof. Mixed silver halide crystals as referred to herein can also be termed solid solutions and, based on X-ray diffraction studies, are deemed to be homogeneous molecular or atomic dispersions in the solid phase of one crystalline substance in another as distinguished from a heterogeneous mixture of crystals of two crystalline substances. Thus, the mixed silver halide, silver bromoiodide, is to be distinguished from a mixture of silver bromide and silver iodide. While silver bromoiodide, or other iodide-containing mixed silver halides, can be utilized to produce the interimage effects of the invention, silver iodide per se is not useful.

In preparing such silver halide emulsions, as well as in preparing the various layers of the present photographic elements, including the layers containing the dye developers, interlayers, topcoat layers and the like, a wide variety of hydrophilic organic colloids can be utilized as the vehicle or carrier. I prefer to utilize gelatin as the hydrophilic colloid or carrier material although such material as polyvinyl alcohol and its water-soluble derivatives and copolymers, water-soluble copolymers such as polyacrylami-de, imidized polyacrylamide, etc., and other water-soluble film-forming materials that form Waterpermeable coats such as colloidal albumin, water-soluble cellulose derivatives, etc., can be utilized in preparing the present photographic elements. Compatible mixtures of two or more of such colloids can also be utilized.

In the present photographic elements, the dye developers are disposed integral with the element and contiguous to silver halide of each of the light-sensitive silver halide emulsion layers. Such dye developers can be incorporated directly in the light-sensitive silver halide emulsion layers or in separate layers contiguous to the layers containing the silver halide.

The various layers utilized in preparing the present photographic elements can be coated on a wide variety of photographic supports. Typical supports include cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film, polyethylene film, polypropylene film, paper, polyethylenecoated paper, glass and the like.

Similarly, a wide variety of receiving sheets can be utilized to receive the dye developer images from the present photographic elements. Typical reception layers for receiving sheets include such materials as linear polyamides, proteins such as gelatin, polyvinyl pyrrolidones, poly-4-vinyl pyridine, polyvinyl acetate, polyvinyl alcohol, cellulose acetate, polyvinyl salicylal, partially hydrolyzed polyvinyl acetate, methyl cellulose, regenerated cellulose, carboxymethyl cellulose and hydroxyethyl cellulose, or mixtures of such. These reception layers can be coated on a suitable support of the type described above for the light-sensitive elements of the invention and include transparent as well as opaque supports. Also, receiving sheets that release acidic material at a controlled rate such as are described in US. Patent 2,584,030 are particularly useful. Such acidic materialsare typically positioned in layers on the receiving sheet below the dye developer reception layer, there suitably being a spacer layer between the acid layer and the mordanting layer to control the release of acidic material. Such acidic materials serve to neutralize residual portions of the alkaline activator on the receiving sheet.

FIG. 1 of the drawings illustrates a typical light-sensitive element or color film of the invention. FIG. 1 also illustrates a typical receiving sheet for receiving dye images from the light-sensitive element and a pod containing processing material positioned between the lightsensitive element and the receiving sheet.

In the light-sensitive element of FIG. 1, on support 10 is coated layer 11 containing a cyan dye developer. Over layer 11 is coated layer 12 which is a red-sensitive silver halide emulsion layer. Over layer 12 is coated interlayer 13. Over layer 13 is coated layer 14 comprising a magenta dye developer. Over layer 14 is coated layer 15 comprising a green-sensitive silver halide emulsion layer. Over layer 15 is coated interlayer 16. Over layer 16 is coated layer 17 containing a yellow dye developer. Over layer 17 is coated layer 18 comprising a blue-sensitive silver halide emulsion layer. Over layer 18 is coated protective layer 19. A receiving sheet comprising support 23 having coated thereon mordant layer 22 can be used to receive dye images from the light-sensitive element during processing when superposed thereon. Positioned between the light-sensitive element and the receiving sheet is rupturable pod 21 containing processing material 20 such as a viscous alkaline aqueous composition. After exposure of the light-sensitive element in a camera to an image, rupturable pod 21 can be ruptured by passing the assembly illustrated in the drawing between rollers in the camera or remote from the camera and the processing composition in the pod uniformly distributed across a predetermined area of the light-sensitive element. The receiving sheet is superposed on the light-sensitive element. The processing composition penetrates through layers 11 to 19, latent images develop in light-sensitive layers 12, 15 and 18 and dye developers in contiguous layers 11, 14 and 17 respectively rendered nondiflusing in areas corresponding to the latent image or negative areas, and the dye developers in the remaining or positive image areas diffuse imagewise in register to mordant layer 22 of the receiving sheet.

Light-sensitive elements of the type illustrated by FIG. 1 typically contain colorless auxiliary developing agents in the emusion layers, overcoat layers or interlayers. Such auxiliary developing agents are described in the art and include such compounds as phenylhydroquinone, Z-hydroxyphenylhydroquinone, phenoxyhydroquinone, 4-methylphenylhydroquinone, dodecylhydroquinone, and the like.

Such light-sensitive elements are advantageously processed in the presence of onium compounds, the onium compounds generally being used in the alkaline processing composition or in the receiving sheet. Such onium compounds are also described in the art and include quaternary phosphonium, tertiary sulfonium and quaternary ammonium compounds. The receiving sheet used to receive dye developer transfer images can contain in its mordant or reception layer such as illustrated by layer 22 of FIG. 1 development inhibitors, e.g. mercapto azoles or the like materials.

FIGS. 2 to 5 of the drawings are characteristic of H and D curves of dye images transferred to receiving sheets on processing photographic elements of the type illustrated in FIG. 1. To obtain the H and D curves of FIGS. 2 to 5 of the drawings, photographic elements of the type de scribed in FIG. 1 were given separate exposures to red, green, blue and white light in an intensity scale sensitometer and thereafter processed as described above and in more detail in the example below with an alkaline solution and the resulting dye developer images transferred to a receiving sheet. The H and D curves of the dye images on the respective receiving sheets were obtained by the general methods described by Hanson and Horton in the Journal of Optical Society of America supra.

FIGS. 2 and 4 illustrate typical H and D curves of the cyan and magenta dyes transferred to receiving sheets that have been prepared with photographic negative elements wherein there is no significant difference in mole percent iodide content of the mixed silver halide in the respective silver halide emulsion layers. FIGS. 3 and 5 of the drawings illustrate typical H and D curves of cyan and magenta dye images transferred from negative elements of the invention and illustrate the interimage effects obtained with the photographic elements of the invention. Such interimage effects as illustrated by FIGS. 3 and 5 manifest themselves as brighter reds and greens respectively in transfer prints. The solid line curves in FIGS. 2 and 3 are the cyan curves of the neutral scale wherein the neutral scale was read through a red filter. The broken line curves in FIGS. 2 and 3 are the cyan curves of the red scale obtained by reading the red scale through a red filter. The solid line curves of FIGS. 4 and 5 are the magenta curves of the neutral scale wherein the neutral scale was read through a green filter. The broken line curves in FIGS. 4 and 5 are the magenta curves of the green scale obtained by reading the green scale through a green filter.

In accordance with the present invention, improvements are not only obtained in the green and red transfer colors as illustrated in the drawings, but also with the blue colors. The positioning of the light-sensitive silver halide emulsion containing the highest mole percent iodide of mixed silver halide in the present three color system can be widely varied. While I prefer that the blue-sensitive silver halide emulsion contain the highest mole percent iodide, the green-sensitive or the red-sensitive silver halide emulsion layers also could be utilized as the high iodidecontent layers. For example, if it is desirable to obtain useful interimage effects monitored by the blue and/or red-sensitive emulsions, the high iodide emulsion would be utilized in the green-sensitive emulsion. Similarly, the high iodide emulsion could be utilized in the red-sensitive emulsion to obtain useful interimage effects monitored in the green and/or blue-sensitive emulsions. In accordance with the invention, it is only necessary that one of the silver halide emulsions of the present photographic elements have at least one mole percent more iodide as mixed silver halide crystals than at least one of the other silver halide emulsion layers.

The invention is illustrated by the following examples of preferred embodiments thereof.

EXAMPLES Several photographic color films having the structure substantially as shown in FIG. 1 of the drawing (layers to 19) were prepared by coating the various layers on a subbed cellulose acetate film support successively with the following layers:

(1). Cyan dye developer layer (e.g., layer N0. 11 of FIG.

1). A coating of cyan dye developer, 5,8-dihydroxy-1- 4 -bis[ 3 hydroquinonyl-a-methyl)ethylamino1anthraquinone, in a high boiling solvent such as N-n-butylacetanilide was dispersed in gelatin and coated at a coverage of 128 mg. per square foot of the the cyan dye developer and 141 mg. per square foot of gelatin.

(2) Red-sensitive emulsion layer (e.g., layer N0. 12 of FIG. 1 ).-A coating of a developing-out negative gelatin-o-silver bromoiodide emulsion sensitized to red light was coated at a coverage of 210 mg. per square foot of silver and 155 mg. per square foot of gelatin.

(3) Interlayer (e.g., layer No. 13 of FIG. 1).-A gelatin layer at a coverage of 200 mg. per square foot.

(4) Magenta a' ye developer layer (e.g., layer N0. 14 of FIG. J).A coating of a magenta dye developer, 4- propoxy-2-[p (p hydroxyquinonylethyl)phenylazo]- l-naphthol, in a high-boiling solvent such as N-n-butylacetanilide was dispersed in gelatin and coated at a coverage of 77 mg. per square foot of magenta dye developer and 77 mg. per square foot of gelatin.

(5) Green-sensitive emulsion layer (e.g., layer No. 15 of FIG. 1).A coating of a developing-out negative gelatino-silver bromoiodide emulsion sensitized to green light was coated at a coverage of 108 mg. per square foot of silver and mg. per square foot of gelatin.

(6) Interlayer (e.g., layer N0. 16 of FIG. 1).A gelatin layer coated at a coverage of mg. per square foot.

(7) Yellow dye developer layer (e.g., layer N0. 17 of FIG. 1).-A coating of the yellow dye developer, 1- phenyl-3-N n hexylcarboxamido-4-[p-(2,5-dihydroxyphenethyl)phenylazo] 5 hydroxypyrazole, dissolved in a high-boiling solvent such as N-n-butylacetanilide and dispersed in gelatin was coated at a coverage of 50 mg. per square foot of the yellow dye developer and 50 mg. per square foot of gelatin.

(8) Blue-sensitive emulsion layer (e.g., layer N0. 18 of FIG. 1).-A coating of a developing-out negative gelatino-silver bromoiodide emulsion that is inherently sensitive to blue light was coated at a coverage of 55 mg. per square foot of silver and 41 mg. per square foot of gelatin.

(9) Protective layer (e.g., layer N0. 19 of FIG. 1).-A

coating containing the colorless auxiliary developer, 4'- methylphenylhydroquinone, at a coverage of 20 mg. per square foot and 40 mg. per square foot of gelatin.

To illustrate the improved interimage effects that are obtained by utilizing a higher mole percent iodide in the mixed silver halide crystals in one of the silver halide emulsion layers of the described photographic element varying amounts of iodide were utilized in the silver bromoiodide of blue-sensitive emulsion layer (e.g., layer 18 of FIG. 1). 4.5 mole percent iodide was used in the silver bromoiodide of the red-sensitive and green-sensitive layers (e.g., layers 12 and 15 of FIG. 1). The various film coatings were given separate exposures to red, green, blue and white light in an intensity scale sensitometer. The resulting exposed films were thereafter processed by applying an alkaline activator solution to the surface thereof I and juxtapositioning thereover receiving sheets comprising a white pigmented cellulose acetate support having a gelatin receiving layer containing a mixture of poly-4-vinyl pyridine mordant and l-phenyl-S-mercaptotetrazole. The receiving sheets and the exposed negative films were left in contact with the alkaline activator material therebetween for a period of about 2 minutes at about 70 F. and thereafter stripped apart. The alkaline activator material comprised an aqueous solution containing 3.5% of high viscosity hydroxyethyl cellulose, 4.5% sodium hydroxide, 2% benzotriazole, 2% l-benzyl-2- picolinium bromide, and 1% sodium thiosulfate. The reflection densities of the graduated scales of the transferred dye developer images on the receiving sheets were then measured. These measurements were then converted mathematically to analytical densities for the particular cyan, magenta and yellow dyes contained in the respective color prints. The analytical densities were plotted against the log exposure to give the usual H and D sensitometric reversal curves. The curves for each of the color scales were compared to the neutral curve for a determination of the interimage effects. More specifically, the cyan dye in the neutral scale was compared with the cyan dye in the red scale. Similarly, the magenta dye in the neutral scale was compared with the magenta dye in the green scale. It was observed that the coatings containing the higher iodide mole percent exhibited substantial density unit differentials at the same exposure (e.g., .8) when compared to the curves representing the cyan dye in the neutral and the cyan dye in the red scale, as well as between the curves representing the magenta dye in the neutral scale and the magenta dye in the green scale. Such density differences at the same exposure represent interimage effects and are illustrated by FIGS. 2 to of the drawings wherein FIGS. 2 and 4 do not utilize higher mole proportions of iodide in the mixed silver halide of the blue-sensitive emulsion. FIGS. 3 and 5 illustrate the substantially greater interimage effects obtained by utilizing a higher mole percent of iodide in the mixed silver halide of the blue-sensitive emulsion layer. Such interimage effects resulted in substantially brighter reds and greens in the color transfer prints. The table below illustrates the improved cyan and magenta interimage effects as a function of increased mole percent iodide in the mixed silver halide of the blue-sensitive emulsion.

TABLE Mole percent iodide in bluesensitive C n C r M rM emulsion layer 1 1 The red and green-sensitive emulsions contained 4.5 mole iodide in all test films.

2 Cn=0.8 density of cyan curve of the neutral scale. O,=thc density of the cyan curve of the red scale at the log exposure where Cn=0-8- 3 Mn=0.8 density of the magenta curve of the neutral scale. M =the density of the magenta curve of the green scale at the log exposure when 1. The process for preparing positive dye developer ditfusion transfer prints wherein an exposed photographic element comprising a support, superposed red, green and blue light-sensitive silver halide emulsion layers, and a dye developer contiguous to said silver halide of each of said silver halide emulsion layers; the said dye developers having in the same molecule both the chromophoric system of a dye and a photographic silver halide developing moiety and being substantially complementary to the color of the spectral sensitivity of the respective contiguous silver halide emulsions; and said silver halide of at least one of said silver halide emulsion layers comprising at least one mole percent more iodide as mixed silver halide than the silver halide in at least one other of said silver halide emulsion layers, is treated with an alkaline solution, developing latent images in the regions of exposure of the silver halide emulsions and thereby immobilizing the dye developers in said regions of exposure, remaining dye developers in undeveloped regions corresponding to a positive image diffusing imagewise to the surface of said photographic element, and transferring the resulting diffused positive dye image in register to a dye developer receiving sheet whereby interimage effects are produced which enhance color saturation of the transferred dye image.

2. The process as described in claim 1 wherein the developing is carried out in the presence of an oniurn compound.

3. The process as described in claim 1 wherein the silver halide of at least one of said emulsion layers comprises predominantly mixed silver halide having about 1 to 20 mole percent iodide and contains at least about 1 mole percent more iodide as mixed silver halide than the silver halide in at least one of the other of said silver halide emulsion layers.

4. The process as described in claim 1 wherein said blue light-sensitive silver halide emulsion layer comprises predominantly mixed silver halide having about 1 to 20 mole percent iodide and contains at least about 1 mole percent more iodide as mixed silver halide and the silver halide in each of said red and green light-sensitive silver halide emulsion layers.

5. The process as described in claim 4 wherein the silver halide in said blue-sensitive layer is composed of silver bromoiodide.

6. A process for preparing positive dye developer diffusion transfer prints wherein an exposed photographic element comprising a support, superposed red, green and blue light-sensitive gelatino-silver halide emulsion layers, and a gelatino layer containing dispersed therein finelydivided droplets of a water-immiscible organic solvent boiling above about C. containing dissolved therein dye developers contiguous to each of said light-sensitive gelatino-silver halide emulsion layers; the said dye developer in the gelatino layer contiguous to said red lightsensitive gelatino-silver halide emulsion being 5,8-dihydroxy-l,4 bis[fl hydroquinony-l-tx-methyl)ethylamino] anthraquinone, the said dye developer in the gelatino layer contiguous to said green light-sensitive gelatinosilver halide emulsion being 4-prop0xy-2-[p-(B-hydroxyquinonylethyl)phenylazo]-1-naphthol, and the said dye developer in the gelatino layer contiguous to said blue light-sensitive gelatino-silver halide emulsion being N-nhexylcarboxamido 4 [p (2',5 dihydroxyphenethyl) phenylazo]-5-hydroxypyrazole; and said silver halide of said gelatino-silver halide emulsion layers consisting essentially of silver bromoiodide having about 1 to 20 mole percent iodide, the silver bromoiodide of said blue lightsensitive gelatino-silver bromoiodide emulsion having at least about one mole percent more iodide than each of said red and green light-sensitive gelatino-silver halide emulsion layers, is treated with an alkaline solution, developing latent images in the regions of exposure of the silver halide emulsions and thereby immobilizing the dye developers in said regions of exposure, remaining dye developers in undeveloped regions corresponding to a positive image diffusing imagewise to the surface of said photographic element, and transferring the resulting diffused positive dye image in register to a dye developer receiving sheet whereby interimage effects are produced which enhance color saturation of the transferred dye image.

7. A photographic element comprising a support, superposed red, green and blue light-sensitive silver halide emulsion layers, and a dye developer contiguous to said silver halide of each of said silver halide emulsion layers; the said dye developers having in the same molecule both the chromophoric system of a dye and a photographic silver halide developing moiety and being substantially complementary to the color of the spectral sensitivity of the respective contiguous silver halide emulsions; and said silver halide of at least one of said silver halide emulsion layers comprising at least one mole percent more iodide as mixed silver halide than the silver halide in at least one other of said silver halide emulsion layers, said iodide in said photographic element producing interimage effects which enhance color saturation when exposed, processed in alkaline media and the resulting image dyes transferred to a receiving sheet.

8. A photographic element comprising a support, superposed red, green and blue light-sensitive silver halide emulsion layers, and a dye developer contiguous to said silver halide of each of said silver halide emulsion layers; the said dye developers having in the same molecule both the chromophor-ic system of a dye and a photographic silver halide developing moiety and being substantially complementary to the color of the spectral sensitivity of the respective contiguous silver halide emulsions; and said silver halide of at least one of said emulsion layers comprising predominantly mixed silver halide having about 1 to 20 mole percent iodide and at least about one mole percent more iodide as mixed silver halide than the silver halide in at least one of the other said silver halide emulsion layers, said iodide in said photographic element producing interimage effects which enhance color saturation when exposed, processed in alkaline media and the resulting image dyes transferred to a receiving sheet.

9. A photographic element comprising a support, superposed red, green and blue light-sensitive silver halide emulsion layers, and a layer containing a dye developer contiguous to each of said light-sensitive silver halide emulsion layers; the said dye developers having in the same molecule both the chromophoric system of a dye and a hydroquinonyl moiety capable of developing photographic silver halide and being substantially complementary to the color of the spectral sensitivity of the respective contiguous silver halide emulsion layers; and said silver halide of said blue light-sensitive silver halide emulsion layer comprising predominantly mixed silver halide having about 1 to 20 mole percent iodide and at least about one mole percent more iodide as mixed silver halide than the silver halide in each of said red and green light sensitive silver halide emulsion layers, said iodide in said photographic element producing interimage effects which enhance color saturation when exposed, processed in alkaline media and the resulting image dyes transferred to a receiving sheet.

10. A photographic element comprising a support, superposed red, green and blue light-sensitive silver halide emulsion layers, and a layer containing a dye developer contiguous to each of said light-sensitive silver halide emulsion layers; the said dye developers having in the same molecule both the chromophoric system of a dye and a hydroquinonyl moiety capable of developing photographic silver halide and being substantially complementary to the color of the spectral sensitivity of the respective contiguous silver halide emulsion layers; and said silver halide of said emulsion layers comprising predominantly silver bromoiodide having about 1 to 20 mole percent iodide, the silver bromoiodide of said blue lightsensitive silver halide emulsion layer having at least about one mole percent more iodide as mixed silver halide than each of said red and green light-sensitive silver halide emulsion layers, said iodide in said blue light-sensitive emulsion producing interimage effects which enhance color saturation when said photographic element is exposed, processed in alkaline media and the resulting image dyes are transferred to a receiving sheet.

11. A photographic element as described in claim 9 wherein the silver halide emulsions are gelatino-silver halide emulsions and the dye developers are dissolved in a water-immiscible organic solvent boiling above about 175 C. and dispersed as finely-divided droplets in gelatin.

12. A photographic element comprising a support, superposed red, green and blue light-sensitive gelatinosilver halide emulsion layers, and a gelatino layer containing dispersed therein finely-divided droplets of a water-immiscible organic solvent boiling above about 175 C. containing dissolved therein dye developers contiguous to each of said light-sensitive gelatino-silver halide emulsion layers; the said dye developer in the gelatino layer contiguous to said red light-sensitive gelatino-silver halide emulsion being 5,8 dihydroxy-1,4-bis[fl-hydroquinonylu-methyDethylamino]anthraquinone, the said dye developer in the gelatino layer contiguous to said green light-sensitive gelatino-silver halide emulsion being 4- propoxy 2 [p-(p-hydroxyquinonylethyl)phenylazo]-1- naphthol, and the said dye developer in the gelatino layer contiguous to said blue light-sensitive gelatino-silver halide emulsion being N-n-hexylcarboxamido-4-[p-(2',5'- dihydroxyphenethyl) phenylazo] -5-hydroxypyrazole; and said silver halide of said gelatino-silver halide emulsion layers consisting essentially of silver bromoiodide having about 1 to 20 mole percent iodide, the silver bromoiodide of said blue light-sensitive gelatino-silver bromoiodide emulsion having at least about one mole percent more iodide than each of said red and green light-sensitive gelatino-silver halide emulsion layers, said iodide in said blue light-sensitive emulsion producing interimage effects which enhance color saturation when said photographic element is exposed, processed in alkaline media and the resulting image dyes are transferred to a receiving sheet.

References Cited UNITED STATES PATENTS 2,221,025 11/ 1940 MacAdam et al 965 2,358,169 9/1944 Kridel 96-103 2,452,765 11/1948 Knott et al. 9619 2,457,005 12/1948 Stevens 5 2,490,751 12/ 1949 Hanson 9669 2,947,628 8/1960 Fierke et al. 96--69 2,968,554 1/1961 Land 963 3,146,102 8/1964 Weyerts et a1 963 3,161,506 12/1964 Becker 963 3,206,313 9/1965 Porter et al. 9619 FOREIGN PATENTS 818,687 8/ 1959 Great Britain.

OTHER REFERENCES Evans et al.: Principles of Color Photography, pages 542-3, John Wiley & Sons, Inc., NY. (1953).

NORMAN o. TORCHIN, Primary Examiner.

G. COHN, Assistant Examiner. 

6. A PROCESS FOR PREPARING POSITIVE DYE DEVELOPER DIFFUSION TRANSFER PRINTS WHEREIN AN EXPOSED PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT, SUPERPOSED RED, GREEN AND BLUE LIGHT-SENSITIVE GELANTINO-SILVER HALIDE EMULSION LAYERS, AND A GELATINO LAYER CONTAINING DISPERSED THEREIN FINELYDIVIDED DROPLETS OF A WATER-IMMISCIBLE ORGANIC SOLVENT BOILING ABOVE ABOUT 175*C. CONTAINING DISSOLVED THEREIN DYE DEVELOPERS CONTIGUOUS TO EACH OF SAID LIGHT-SENSITIVE GELATINO-SILVER HALIDE EMULSION LAYERS; THE SAID DYE DEVELOPER IN THE GELATINO LAYER CONTIGUOUS TO SAID RED LIGHTSENSITIVE GELATINO-SILVER HALIDE EMULSION BEING 5,8-DIHYDROXY-1,4-BIS(B-HYDROQUINONYL-X-METHYL)ETHYLAMINO) ANTHRAQUINONE, THE SAID DYE DEVELOPER IN THE GELATINO LAYER CONTIGUOUS TO SAID GREEN LIGHT-SENSITIVE GELATINOSILVER HALIDE EMULSION BEING 4-PROPOXY-2-(P-(B-HYDROXYQUINONYLETHYL)PHENYLAZO)-1-NAPHTHOL, AND THE SAID DYE DEVELOPER IN THE GELATINO LAYER CONTIGUOUS TO SAID BLUE LIGHT-SENSITIVE GELATINO-SILVER HALIDE EMULSION BEING N-NHEXYLCARBOXIMIDO-4-(P-(2'',5''-DIHYDROXYPHENETHYL) PHENYLAZO)-5-HYDROXYPYRAZOLE; AND SAID SILVER HALIDE OF SAID GELATINO-SILVER HALIDE EMULSION LAYERS CONSISTING ESSENTIALLY OF SILVER BROMOIODIDE HAVING ABOUT 1 TO 20 MOLE PERCENT IODIDE, THE SILVER BROMOIODIDE OF SAID BLUE LIGHTSENSITIVE GELATINO-SILVER BROMOIODIDE EMULSION HAVING AT LEAST ABOUT ONE MOLE PERCENT MORE IODIDE THAN EACH OF SAID RED AND GREEN LIGHT-SENSITIVE GELATINO-SILVER HALIDE EMULSION LAYERS, IS TREATED WITH AN ALKALINE SOLUTION, DEVELOPING LATENT IMAGES IN THE REGIONS OF EXPOSURE OF THE SILVER HALIDE EMULSIONS AND THEREBY IMMOBILIZING THE DYE DEVELOPERS IN SAID REGIONS OF EXPOSURE, REMAINING DYE DEVELOPERS IN UNDEVELOPED REGIONS CORRESPONDING TO A POSITIVE IMAGE DIFFUSING IMAGEWISE TO THE SURFACE OF SAID PHOTOGRAPHIC ELEMENT, AND TRANSFERRING THE RESULTING DIFFUSED POSITIVE DYE IMAGE IN REGISTER TO A DYE DEVELOPER RECEIVING SHEET WHEREBY INTERIMAGE EFFECTS ARE PRODUCED WHICH ENHANCE COLOR SATURATION OF THE TRANSFERRED DYE IMAGE.
 7. A PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT, SUPERPOSED RED, GREEN AND BLUE LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYERS, AND A DYE DEVELOPER CONTIGUOUS TO SAID SILVER HALIDE OF EACH OF SAID SILVER HALIDE EMULSION LAYERS; THE SAID DYE DEVELOPERS HAVING IN THE SAME MOLECULE BOTH THE CHROMOPHORIC SYSTEM OF A DYE AND A PHOTOGRAPHIC SILVER HALIDE DEVELOPING MOIETY AND BEING SUBSTANTIALLY COMPLEMENTARY TO THE COLOR OF THE SPECTRAL SENSITIVITY OF THE RESPECTIVE CONTIGUOUS SILVER HALIDE EMULSIONS; AND SAID SILVER HALIDE OF AT LEAST ONE OF SAID SILVER HALIDE EMULSION LAYERS COMPRISING AT LEAST ONE MOLE PERCENT MORE IODIDE AS MIXED SILVER HALIDE THAN THE SILVER HALIDE IN AT LEAST ONE OTHER OF SAID SILVER HALIDE EMULSION LAYERS, SAID IODIDE IN SAID PHOTOGRAPHIC ELEMENT PRODUCING INTERIMAGE EFFECTS WHICH ENHANCE COLOR SATURATION WHEN EXPOSED, PROCESSED IN ALKALINE MEDIA AND THE RESULTING IMAGE DYES TRANSFERRED TO A RECEIVING SHEET. 